Vacuum-tube lamp.



D. McF. MOORE.

VACUUM TUBE LAMP.

APPLICATION FILED NOV. 26, 1904.

Patented Aug. 6, 1912.

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ATTORNEY UNITED STATES PATENT-OFFICE.

DANIEL MOFARLAN MOORE, OF NEWARK, NEW JERSEY, ASSIGNOR' TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

VACUUM-TUBE LAMP.

Application filed November 26, 1904. Serial No. 234,339.

To all whom it may concern: 1

Be it known that I, DANIEL McFAnLAN Moons, a-citizen of the United States, and a resident of Newark, in the county of Essex and State of New Jersey, with post-oflice address 52 Lawrence street, have invented certain new and useful Improvements in Vacuum-Tube Lamps, of which the following is a specification.

My present invention relates to that class of devices employed for lighting and other purposes, and comprising essentially a sealed receptacle containing a rarefied air or other gas through which electric energy is passed for the purpose of rendering the contents of-the receptacle luminous, or for other purposes.

My invention is useful not only for lamps in which the electric energy 'is transferred electrostatically to the contents of the tube by exterior conducting caps but also and particularly for those employing internal or sealed electrodes.

Briefly stated, my invention consists in the provision within the lamp of an improved substance which acts to increase the life of the lamp, give steadiness to the light and secure other adv'antages. In. my prior application filed Sept. 2nd, 1903, S. N. 171,587, I have described the use for these purposes 7, within the lamps of various organic substances and in my application filed May 25th, 1904, Patent No. 854,104, dated May 21st, 1907, I have described the use of graphitic oxid or as it is sometimes called graphitic acid, but the latter substance is in general not so suitable for internal electrode lamps as for external electrode lamps since the internal electrode lamps are provided with much smaller electrodes. Therefore the resultant temperature is too high for best operation of graphitic oxid.

One of the purposes of my present invention is to overcome this difliculty.

Broadly stated my present invention consists of a vacuum tube lamp containing a substance composed only or entirely of carbon hydrogen and oxygen and preferably one of the t-riphenyl methane. group among which I have found ordinar shellac to be the most suitable, although I have also employed the substance known as rosolic acid. Shellac belongs to the gum or resin class of compounds like sandarac, hereinafter mentioned. The general formula for shelllac or lac or gum lac or gums is (C H O The chemical name of rosolic acid which is known as an acid dye, is tripara oxytolyl diphenyl carbinol anhydrid and its formula as ordinarily known is C H O In organic chemistry it comes under the head of triphenyl methane group, which is divided into four heads one of which is the aurin group and one of its derivatives being rosolic acid. As my invention includes all substances containing carbon, hydrogen and oxygen only, and as above stated, it includes obviously sugar from which I have obtained fair results.

\Vhile my invention includes tube lamps of any form and embraces such lamps having the substance or chemical introduced into or included in the. lamp in any desired manner, I have herein shown the same as applied to lamps having internal electrodes such as described in my prior Patent No. 749,998 dated Jany. 19, 1904 in which case the improved chemical may be mixed with some conduct-ing material like graphite which is applied as a coating within the lamp and to the electrodes. I have obtained the best coatings by a mixture of two parts of graphite with one of shellac and this made into a paste by using alcohol. Shellac for this purpose is preferable principally because this form of paste actslike a varnish, that isit sticks to the glass and can be made to dry in a hard coating free from cracks. Another distinguishing feature is that it is not volatile. When used with too much graphite it is liable to soil the tube for a yard or so ahead of the terminal. This is not the case however when powdered metal, for instanceiron or aluminum, is used in place of graphite. While the chemical is useful of itself special provisions are desirable when it is embodied with or forms a part of the conducting terminal within the lamp. It is desirable to first make a small coating which covers only the platinum or other terminal and on this to apply a longer or more extensive coating which forms as it were an expanded terminal or one of large area adapted to permit the lamp to be run with heavy currents butwithout undue heating or decomposing efl'ects. This small coating may be made by mixing five parts graphite and one part shellac with grain alcohol to the consistency of glue. It is packed all around the leading-1n wires,

Patented Aug. 6, 1912.

then dried with an air-blast and then slowly heated until the white vapors arising from it have ceased. Such a patty will not be destroyed, that is dissolved, by the large coating when it is'put in the tube. The mixture of the rosolic acld powder with the graphite is ground in a mortar and then the alcohol added until it. has reached the consistency of thick cream, when it is poured into the tube while it is in a vertical position. The tube is then tilted slightly downward and rotated so that the mixture works its way toward the mouth of the short tube and thereby coats its interior. The surplus coating simply runs out the mouth. Then by means of exterior heat and interior air-blast the coating is dried. Then, before it is thoroughly dry it is wifped away for a distance about two inches rom the mouth with a cloth moistened with alcohol, so that such terminal can be sealed onto the long light portion of the tube without burning the electrode proper.

In the accompanying drawings, Figure 1 shows in longitudinal section one end of' a vacuum tube lamp the leading-in wire being indicated at 1, the branched end thereof at 2, the part called the patty at 3, and the expansion of the terminal at 4. The light portion of the tube is indicated at 5. Figs. 2 and 3 illustrate modified forms of lamp.

While I have found the shellac very suitable for the purpose aurin or coralline also might be used. I have also used the resin known as sandarac which is a mixture of a number of chemicals all of which however consist only of carbon hydrogen and oxygen. Cellulose C H O has also been used by me.

The tube furnished with the improved material is exhausted in the usual way during the passage of current through the tube and is sealed off when the deslred degree of luminosity is reached.

The action of the improved chemical cannot be stated with great exactness but in general it may be said that under the action of the electricity and the heat there results a peculiar gas or gaseous condition and that the effect of the electric current passing through such gas is to render the same luminous. The condition of heat may come simply from the internal heating of the lamp by the electric currents or extraneous means for heating and controlling the heat may be employed.

By the use of my invention vacuum tube lamps may be run direct from street circuits carrying alternating currents of 60 cycles and at the same time the luminous portion of the lamp may be of great length.

Another modification of the method of applying this invention is shown in Fig. 2, in which the chemical placed within the tube for the purpose of furnishing the gaseous conductor is not a part of the coating, or

' electrode proper, as shown in Fig. 1, but is placed upon the walls of the tube in a position entirely insulated and isolated from the electrode proper, which in this case consists of a pencil of graphite supported upon the glass stud containing the leading-in wires. The chemical as shown is placed opposite the rear portion of the electrode purposely because a good light giving tube consists essentially of a thoroughly ionized gas, and when the gaseous vapors are given off by the chemical coating or powder (8) they receive their first and principal ionization while passing through the annular space around the electrode.

Another method of practising this invention is shown in Fig. 3, wherein the chemical is shown in a tube (6) extending from of an electric heater in the form of a hollow cylinder to which is applied an electric heating coil. Main electrode (9) has its bottom perforated so that when the vapors pass from the chemical it is necessary for all of them to pass through the electrode and then be ionized before entering the light column proper. A further advantage is gained in that the portion of the main tube covering the electrodes proper (11) can-be -kept cool, comparatively speaking, that is, its temperature can remain constant. The natural tendency of most heretofore properly constructed internal electrode tubes has been to have the vacuum gradually get higher, that is, less pressure within the vacuum and, assuming constant voltage, its total watts gradually increase until a certain maximum is reached, which is generally coincident with the maximum efficiency for the given gas, shortly after which'the tube refuses to take any watts at all. This ditiiculty is shown overcome in Fig. 3, by placing the heater (7 in' series with the tube circuit so that as the watts naturally tend to increase the heat will also increase, thereby furnishing more gases or vapors, preventing the vacuum from getting too hlgh or may be simply heating the chemical until it is in a proper condition to reunite with the gases that have once been ionized and then neutralized by collision.

I do not claim herein the manner of regulating the rate at which gas shall be furnished to the tube by the operation of a regulating coil in a irect working circuit of the tube as shown in Fig. 3, since this is the subject of a claim in another application for patent filed by me of even date herewith No. 234,340.

What I claim as my invention is:

1. A vacuum tube lamp containing a nonvolatile substance composed of carbon hydrogen and oxygen only.

2. An electrically operated vacuum tube containing a hydrogen oxygen carbon comthe main electrode tube and heated by means pound belonging to the triphenyl methane group.

3. A vacuum tube having an internal electrode comprising a mixture of a conducting material and an organic substance.

4. A vacuum tube having an internal electrode comprising a mixture of a conducting material and a compound of hydrogen oxygen and carbon.

5. A vacuum tube having an internal electrode comprising a mixture of carbon and an organic substance.

6. A vacuum tube having an internal electrode comprising a mixture of carbon and it) compound of hydrogen oxygen and car- 7. A vacuum tube having an internal electrode comprising a mixture of graphite and an organic substance.

8. An electrically operated vacuum tube containing shellac as and for the purpose described.

9. A vacuum tube having an internal electrode comprisinga conductor combined with shellac.

10. A vacuum tube having an internal electrode comprising a mixture of carbon and shellac.

11. A vacuum tube having an internal elect-rode comprising a mixture of graphite and shellac.

12. An internal electrode vacuum tube having an entering conductor terminating within the lamp in a coating comprising a mixture of a conducting material and an organic substance, said coating serving to give a terminal of relatively large superficial area as and for the purpose described.

13. An internal electrode vacuum tube having an entering conductor terminating within the tube in a coating comprising a mixture of a conducting material and a compound of hydrogen oxygen and carbon, said coating serving to give a terminal of relatively large superficial area as and for the purpose described.

14. An internal electrode vacuum tube having an entering conductor terminating within the lamp in a coating comprising a mixture of graphite and an organic substance, said coating serving as a terminal of relatively large superficial area as and for the purpose described.

15. An internal electrode vacuum tube having an entering conductor terminating Within the lamp in a coating comprising a mixture of carbon and a compound of hydrogen oxygen and carbon.

16. An internal electrode vacuum tube having anentering conductor terminating in a coating comprising a mixture of graphite and an organic substance, said coating serving as a terminal of relatively large superficial area as and for the purpose described.

17. An internal electrode vacuum tube having an entering conductor terminating in a coating comprising a conducting substance combined with shellac, said coating constituting a terminal of relatively large superficial area as and for the purpose described.

18. In a vacuum tube an electrode comprising a coating formed of a gas evolving chemical mixed with a conductor.

Signed at New York in the county of New York and State of New York this 23d day of November A. D. 1904.

DANIEL MCFARLAN MOORE.

Witnesses:

C. T. TISOHNER, Jr., A. FRANKENTHALER. 

